One of the problems associated with the collection and treatment of domestic sewage is the occurrence of volatile odorous substances. These odorous compounds generally contain divalent sulfur, nitrogen and/or carbonyl oxygen. Quite abundant among the odor bearing compounds are sulfides and thiols, but the most important among these is hydrogen sulfide. Because of the prominence of this compound and other sulfides as the main odor-bearing constituents in sewage, this application is directed to the control of H.sub.2 S (the gaseous form) and other sulfides (the dissolved form in water) for the control of the odor and sulfide content in sulfide containing water. The terms hydrogen sulfide (H.sub.2 S) and other sulfides of divalent sulfur are used interchangeably.
H.sub.2 S and most of the other odorous sulfur compounds result from biological activity, particularly the anaerobic decomposition of compounds containing sulfur. The most common starting materials for hydrogen sulfide (H.sub.2 S) is sulfate ion (SO.sub.4.sup.2-). In the absence of oxygen, certain bacteria such as, for example, Desulfovibrio desulfuricans will metabolize sulfate ion along with diverse organic matter present according to the following equation: ##STR1##
Hydrogen sulfide possesses a characteristic rotten egg odor, is toxic even in low concentrations and also highly corrosive towards steel and concrete. Its presence in air and waste water is therefore highly undesirable and its cost effective control is an important aspect of sanitary waste management.
Waste collection systems for sewage serve the purpose of conveying domestic sewage from the point of generation (for example, residences) to the treatment plant. These collection systems usually consist of many miles of concrete or iron pipe, of a wide variety of sizes. Sewage flow is effected by either gravity or the use of pumps (force mains). Hydrogen sulfide can escape from the sewage through manholes and air vents as well as via lift stations. In a sewer pipe, the actual location of bacterial action is a slimy biofilm attached to the pipe wall. Under certain conditions, bacteria present in this layer can convert sulfate ion into sulfide. Conditions favorable for sulfide generation in municipal sewage are: the presence of sulfate ion in appreciable concentrations combined with a low redox potential; the absence of dissolved oxygen and other oxidants; also the absence of nitrates and nitrites. Sulfides, however generated, are a toxicity hazard as well as an undesirable corrosive material deleterious to steel and concrete used in waste collection systems.
It is an object of the invention to control the sulfide content of sulfur containing water.
It is an object of the invention to provide a composition for the removal of odors from sulfide containing water.
It is another object of the invention to provide a method for controlling the odor of sulfide containing water.
Still further objects and advantages of the invention will be found by reference to the following description.